Near Alliance base there are troll patrol flying on ptero, just hit the mount and it will drop the troll, take him near a ward (possibly avoid guards) hit him a couple times then wait for the wards to kill the troll

Near Sunreavers base is little beach where are few trolls (one named, Nurkala) and raptor. All you need to do is to arm the ward, pull mobs to it, kill all except one (and get him to like 5-10% hp), then wait for the ward to kill troll. Gz, you just get achievement :P

I did it first try accidently, i activated the ward on the far right side next to the guards fighting the trolls, didnt even tag a troll, just clicked the ward, it killed a troll in 1 hit, and i got credit.

I play alliance, so this was the far right ward at the bottom of the steps in the water.

I think you're supposed to use it on a player from the opposing faction as that's what got me the achievement. Had an ally around the ward area and myself and a guildie got him down to 10% then activated the ward.

Prior to that I was pulling random mobs near them and the wards wouldn't do anything when activated.

try pulling the mob to one of the wards that is off to the side so it is less likely an NPC will also start to attack the alliance or troll mob. (seems to only work with players ofthe opposing faction or trolls).

First time I did it the patrolling arcane construct got the killing blow. No achievement.

My name is Cernunnos, I will love you like no other, I have died a thousand deaths, each time I died I thought of you.